A STUDY OF MESSENGER RNA EXPRESSION IN RUPTURED BICEPS TENDON

Abstract

Aim: To study mRNA expression in ruptured biceps tendon.

Methods: Our study was carried out in the University College of Medicine. We took the biceps tendon of 5 patients who had traumatic ruptures. The age of the patients ranged from 35–53. The tendons were processed for RNA isolation and reverse-transcription-polymerase chain reaction (RT-PCR) carried out in order to investigate the mRNA gene expression in ruptured biceps tendon of extra cellular matrix (ECM) components (e.g. proteoglycans and collagens); ECM degradative components (e.g. aggrecanases and MMPs); inflammatory components (e.g. cytokines and cyclooxygenases); and factors involved in the apoptotic response.

Results: Our results showed that in the samples of ruptured biceps tendon there was a good mRNA expression of ECM structural components, especially aggrecan and the small proteoglycans biglycan and decorin. Interestingly, these samples also showed a high expression for the enzymes commonly involved in articular cartilage degradation and turnover, the aggrecanases (ADAMTS-4 and –5) and the matrix metalloproteinases (MMP-3 and –13). As has been recently reported for Achilles tendon rupture (Cetti et al, 2003), an inflammatory reaction was also observed in these ruptured bicep tendons with expression of the inflammatory cytokines IL-1α and TNFα and the enzyme cyclooxygenase-2.

Conclusion: We know clinically that patients can rupture their biceps tendon either due to trauma if not due to degenerative conditions. In our study we wanted to know if the subset of patients who ruptured their tendons traumatically had any pre-existing degenerative conditions leading on to the rupture compared to the normal subjects. Interestingly our study has shown that there is mRNA expression of degradative enzymes (aggrecanases and MMPs) in the samples of ruptured biceps tendon. Whether these mRNA levels equate to increased enzyme activity of these molecules warrants further investigation. Furthermore, our samples also showed mRNA expression for factors involved in the inflammatory response. In conclusion, mRNA expression of the factors involved in degradation and inflammation may suggest a phenotype that predisposes the bicep tendon to rupture, although further studies are required in order to investigate this further.